1. Field of the Invention
The present invention relates generally to a fan hub balancing structure, and more particularly to a fan hub balancing structure in which the residual weight sections are removed from the hub main body by means of punching or perforating the lip section of the hub main body so as to provide a balancing effect for the hub main body.
2. Description of the Related Art
The hubs of the conventional computer fans are generally made of metal material or plastic material. In the manufacturing process of the fan, in order to operate the fan in an optimal balanced state without unnecessary vibration, a defective product is processed in a reduce-to-balance manner. That is, the residual weight sections of the hub are removed from the hub so as to balance the hub. With a metal-made (such as iron-made) hub taken as an example, a conventional metal-made hub is punched and molded by a mold. When punched by the mold, the metal hub can hardly have a uniform thickness. Therefore, after molded, the metal hub will have non-uniform weight. As a result, the metal hub will be over-unbalanced. In order to solve the problem of unbalance of the metal hub, the punch mold is rectified to adjust the geometrical tolerance (such as the concentricity, the run-out and the perpendicularity) so as to improve the unbalance amount of the molded metal hub.
However, the above method can hardly effectively improve the unbalance amount of the metal hub. This is because the weight of the surface of the top section and the weight of the surface of the circumferential section of the metal hub are not substantially decreased or increased. The punch mold is simply shifted and adjusted so that the unbalance amount can be hardly improved.
In the conventional metal hub balancing structure, a mold is used to punch the top section 11 of the metal hub 1 so as to remove the material of the over-weighing angular position. This can provide a balancing effect for the metal hub 1. The unbalance amount of the metal hub 1 can be improved by means of the above punching method. However, this leads to another problem. That is, the top section 11 of the metal hub 1 is formed with a central opening 111 for a shaft to insert therein. A recess 113 is formed around the opening 111. Therefore, when punching the top section 11 of the metal hub 1 to remove the material from the top section 11 so as to balance the metal hub 1, due to the affection of the recess 113, the total structural strength of the top section 11 will be deteriorated.
In addition, the current punch mold has an upper punch mold section and a lower punch mold section. Therefore, the surface of the circumferential section 12 of the metal hub 1 cannot be punched to improve the unbalance amount of the metal hub 1. In the case that the circumferential section 12 of the metal hub 1 is 90-degree turned to make a circumferential surface and an opposite circumferential surface of the circumferential section 12 respectively face the upper and lower punch mold sections of the punch mold, neither the inner side of the circumferential surface of the circumferential section 12 nor the inner side of the opposite circumferential surface of the circumferential section 12 is supported by any support article. As a result, when the circumferential surface of the circumferential section 12 is punched by the upper punch mold section, the entire circumferential section 12 of the metal hub 1 will be seriously deformed and the perforations will have burrs. In some more serious cases, the magnets received in the metal hub may be scraped or deformed by the burrs of the perforations.
It is therefore tried by the applicant to provide a fan hub balancing structure to overcome the problems of the conventional structure. The fan hub balancing structure of the present invention is able to provide a balancing effect for the hub main body without increasing the thickness of the hub main body so as to meet the requirement of lightweight and slimness or deteriorating the structural strength of the top section and the circumferential section of the hub main body.